Circuit arrangement for charging a DC link capacitor with electrical energy are generally known. The DC link capacitor in this case serves the purpose of providing currents for a short-term high current requirement of a consumer to be supplied electrical energy from the battery. In order to charge the DC link capacitor with electrical energy, said DC link capacitor is in particular connected in parallel with the charging battery.
At the beginning of a charging operation, the at least one switching element can be closed and the DC link capacitor can be electrically conductively connected directly to the charging battery. Owing to the physical properties of the DC link capacitor, in the case of a direct connection between the charging battery and the DC link capacitor, however, a comparatively high current would flow from the charging battery to the DC link capacitor, in particular at the beginning of the charging operation. Such a high current can overload the charging battery, for example, and possibly even damage it.
In order to at least temporarily limit the charging current, the known circuit arrangements have a charging resistor which can be connected in parallel with the first switching element. The charging resistor is generally an ohmic resistor, which is connectable to the charging battery and/or the DC link capacitor with the aid of a further switching element and is thus capable of bypassing the first switching element. Since the further switching element needs to be capable of switching high currents at high voltages, for example of up to 600 V, the switching element generally requires a large amount of installation space and has a high weight. In particular when using the circuit arrangement in a motor vehicle, however, installation space is scarce and a high weight is disadvantageous. Even in stationary applications, for example in wind turbines, installation space can be limited.